1. Field of the Invention
The present invention concerns steam generator feed water heaters, especially for power stations in which the steam produced drives one or more turbines.
2. Description of the Prior Art
For improved energy efficiency the steam generator feed water is pre-heated in a heat exchanger or heater using as heating fluid bleed steam and condensates recovered from the outlets of various units of the system such as driers and condensors.
Using condensates to feed the heaters is favorable to the overall energy balance of the installation; the usable heat recovered in this way can represent a significant fraction (15 to 25%) of the heat employed.
As a general rule, a heater has an elongate pressurized enclosure comprising in the vicinity of one end at least one condensate inlet tube. Experience shows that because of the turbulence of the incoming flow, which generally expands inside the heater, the parts adjacent the inside wall are exposed to violent erosion leading to a relatively rapid reduction in their thickness.
To overcome this problem it has been proposed to provide within the enclosure, facing the condensate inlet tube, an impact wall intended to dissipate some of the kinetic energy of the jet of condensate issuing from this tube. In practice, however, the speed of the flow of condensate at the walls remains high and the erosion phenomena remain.
In another prior art solution the walls of the enclosure are made from a steel that resists erosion. This solution entails high manufacturing costs, however, the alloy employed being costly and difficult to use.
An object of the invention is to alleviate these disadvantages by means of a specific arrangement of the way in which condensates are admitted to the heated enclosure.